JP2014149639A - Startup circuit, semiconductor device, and method of starting semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a startup circuit, a semiconductor device, and a method of starting the semiconductor device, in which a constant current generation circuit can be reliably started in an automatic startup method and unnecessary current can be prevented from flowing after the startup is complete.SOLUTION: When a detection circuit 20 detects an operation failure of a bias circuit 12, a startup circuit 14 controls the potential of a gate of a PMOS transistor P3 of a supply element 22 according to the sum of the off-resistance of a PMOS transistor P4, the on-resistance of an NMOS transistor N3, the on-resistance of a PMOS transistor P5, and the off-resistance of a PMOS transistor P6. When the bias circuit 12 causes the operation failure, the startup circuit 14 controls the on and off of the PMOS transistor P3 so as to supply a startup current to the bias circuit 12, thereby enabling the bias circuit 12 to reliably being started.

Description

  The present invention relates to a startup circuit, a semiconductor device, and a startup method of a semiconductor device.

  Conventionally, a reference current generating circuit (hereinafter referred to as a bias circuit) is used in a system (such as a microcomputer or LSI). Specific examples of such a bias circuit include, for example, the bias circuits shown in FIGS.

  When a start signal can be input from the outside of the system, a circuit method for starting the bias circuit by using the start signal can be used. However, depending on the use environment, various conditions, etc., the operation may not occur.

  Further, for example, when the bias circuit is used in a system main power supply circuit or the like, a signal from the system cannot be obtained unless the main power supply circuit is activated.

  For this reason, in general, in a bias circuit, a start-up circuit is mounted at the time of power-on or after the power-on to prevent the bias circuit from failing to operate. In addition, mounting a start-up circuit is in demand from the recent trend of lower current consumption.

  Moreover, there is a concern that it will be difficult to obtain an activation signal from the outside due to the difference in voltage level between the system and the external interface as the number of power sources increases from that of a single power source in the future. Also in the system, it is required to incorporate a power supply circuit due to the influence of a single power supply.

  For this reason, an automatic startup method type startup circuit is required for the bias circuit. As an automatic startup type semiconductor device in which such a startup circuit is mounted on the bias circuit, for example, the technique disclosed in Patent Document 1 is known. It has been.

JP 2011-118532 A

  However, even when an automatic startup type startup circuit is used, operation failure may occur as described above. For example, an operation failure may occur due to the influence of variations in elements of the starting circuit and the bias circuit.

  Further, even after the start-up is completed, the start-up current used for starting the bias circuit continues to flow, and unnecessary current may flow.

  The present invention provides a startup circuit, a semiconductor device, and a startup method of a semiconductor device that can reliably start up a constant current generation circuit in an automatic startup system and can suppress an unnecessary current from flowing after the startup is completed. The purpose is to do.

  In order to achieve the above object, a starting circuit of the present invention includes a control terminal, a supply element that supplies a starting current to a constant current generating circuit according to a voltage applied to the control terminal, and a control of the supply element A first element connected between the control node connected to the terminal and the first potential portion; and a plurality of second elements connected between the control node and a second potential portion different from the first potential portion. And a control unit that controls supply of the starting current by the supply element, and the control unit has an element resistance of the first element when the constant current generation circuit is in a first power state. Is larger than the sum of the element resistances of the plurality of second elements, and when the constant current generation circuit is in the second power supply state, the element resistance of the first element is Is smaller than the sum of the element resistances.

  The semiconductor device of the present invention includes a constant current generating circuit and a starting circuit of the present invention.

  According to another aspect of the present invention, there is provided a method for starting a semiconductor device, comprising: a control terminal; a supply element that supplies a start-up current to a constant current generation circuit according to a voltage applied to the control terminal; A first element connected between the control node and the first potential portion, and a plurality of second elements connected between the control node and a second potential portion different from the first potential portion. And a controller for controlling the supply of the startup current by the supply element, wherein the constant current generation circuit is in the first power supply state when the constant current generation circuit is in the first power supply state. A step of supplying a starting current to the constant current generation circuit by the supply element, wherein the resistance is greater than a sum of element resistances of the plurality of second elements; In this case, the element resistance of the first element is Smaller than the sum of the respective element resistance of the plurality of second devices, and a step of stopping the supply of the starting current by the supply device.

  According to the present invention, it is possible to reliably start the constant current generating circuit in the automatic starting method and to suppress an unnecessary current from flowing after the starting is completed.

It is a circuit diagram showing an example of a semiconductor device of the 1st example. It is a circuit diagram which shows an example of the semiconductor device of a 2nd Example. It is a circuit diagram which shows an example of the semiconductor device of a 3rd Example. It is a circuit diagram which shows an example of the semiconductor device of a 4th Example. It is a circuit diagram which shows another example of a semiconductor device. It is a circuit diagram which shows an example of a bias circuit. It is a circuit diagram which shows another example of a bias circuit. FIG. 7 is a circuit diagram showing an example of a semiconductor device of a comparative example in which a conventional startup circuit is applied to the bias circuit shown in FIG. 6. FIG. 8 is a circuit diagram showing an example of a semiconductor device of a comparative example in which a conventional startup circuit is applied to the bias circuit shown in FIG. 7.

Hereinafter, examples according to the present embodiment will be described in detail with reference to the drawings.
(First embodiment)
First, the configuration of the semiconductor device of this embodiment will be described. FIG. 1 shows a circuit diagram of an example of the semiconductor device of this embodiment. As shown in FIG. 1, the semiconductor device 10 of this embodiment includes a bias circuit 12 and a starting circuit 14.

  The bias circuit 12 of this embodiment includes a PMOS transistor P1, a PMOS transistor P2, an NMOS transistor N1, an NMOS transistor N2, and a resistor R1.

  The source of the PMOS transistor P1 is connected to the power supply Vdd, and the drain is connected to the drain of the NMOS transistor N1. The source of the PMOS transistor P2 is connected to the power supply Vdd, and the drain is connected to the drain of the NMOS transistor N2. The gate of the PMOS transistor P1 and the gate of the PMOS transistor P2 are connected to each other. Each gate is connected between the PMOS transistor P1 and the NMOS transistor N1 by a node vp that functions as a detection node.

  The source of the NMOS transistor N1 is connected to the ground GND via the resistor R1, and the drain is connected to the drain of the PMOS transistor P1. The source of the NMOS transistor N2 is connected to the ground GND, and the drain is connected to the drain of the PMOS transistor P2. The gate of the NMOS transistor N1 and the gate of the NMOS transistor N2 are connected to each other. Each gate is connected between the PMOS transistor P2 and the NMOS transistor N2 by a node vn functioning as a detection node.

  The bias circuit 12 generates a reference current that makes the reference current Iref1 and the reference current Iref2 equal by the potential difference between the source and gate of the NMOS transistor N1 and the NMOS transistor N2 and the resistor R1.

  The bias circuit 12 generates a reference current Iref1 and a reference current Iref2 with such a state as an operation stable point. However, the bias circuit 12 also has an operation stable point in a state where Iref1 = Iref2 = 0 (a state where no reference current flows). Specifically, in a state where there is no difference between the gate-source voltages of the NMOS transistor N1 and the NMOS transistor N2, a reference current is not generated, and an operation stable point of Iref1 = Iref2 = 0 is obtained.

  On the other hand, the activation circuit 14 includes a detection circuit 20 and a supply element 22.

  The supply element 22 is an element having a function of flowing a starting current to the bias circuit 12, and in the present embodiment, a PMOS transistor P3 is used. The source of the PMOS transistor P3 is connected to the power supply Vdd, and the drain is connected to the node vn of the bias circuit 12. The gate of the PMOS transistor P3 is connected to the detection circuit 20 by the node vs. In the present embodiment, the node vs functions as a control node that controls the inflow of the starting current by the supply element 22.

  The detection circuit 20 has a function of detecting the power supply state (potential) state of the bias circuit 12 and controlling inflow of the starting current by the supply element 22 according to the detected voltage. In the detection circuit 20 of this embodiment, a PMOS transistor P4, an NMOS transistor N3, a PMOS transistor P5, and a PMOS transistor P6 are connected in series between the power supply Vdd and the ground GND. The PMOS transistor P4 has a source connected to the power supply voltage Vdd and a drain connected to the node vs. The drain of the PMOS transistor P4 is connected to the drain of the NMOS transistor N3.

  The drain of the NMOS transistor N3 is connected to the node vs, and the source is connected to the source of the PMOS transistor P5. The gate of the PMOS transistor P4 and the gate of the NMOS transistor N3 are connected to the node vp of the bias circuit 12.

  The source of the PMOS transistor P5 is connected to the source of the NMOS transistor N3. The drain of the PMOS transistor P6 is connected to the ground GND. The drain of the PMOS transistor P5 and the source of the PMOS transistor P6 are connected via a node vs. The gate of the PMOS transistor P5 is connected to the node vn of the bias circuit 12. The gate of the PMOS transistor P6 is connected between the NMOS transistor N3 and the PMOS transistor P5 by the node vs2.

  The gates connected to the node vp of the bias circuit 12 and the gate connected to the node vn function as activation detection terminals for detecting the power supply state (potential) of the bias circuit 12.

  Next, the operation of the semiconductor device 10 of this embodiment will be described.

  First, a description will be given of a case where an operation stable point is obtained in a state where reference current Iref = reference current Iref2 = 0, which is an operation failure at start-up. In this embodiment, the state in which the bias circuit 12 does not operate and the reference current Iref = reference current Iref2 = 0 is referred to as “operation failure”.

  In this case, the potential of the node vp is the power supply level (Vdd). The potential of the node vn is at the ground level (GND).

  Since the node vp is at the power supply level (Vdd), the PMOS transistor P4 is turned off, resulting in a very large off resistance.

  Since the node vp is at the power supply level (Vdd), the NMOS transistor N3 is turned on. Further, since the node vn is at the ground level (GND), the PMOS transistor P5 is turned on. The NMOS transistor N3 and the PMOS transistor P5 have a small on-resistance.

  Since the MOS transistor N3 and the PMOS transistor P5 are on, the PMOS transistor P6 is off. The potential of the node vs2 to which the gate is connected and the potential of the node vs3 to which the source is connected are almost at the ground level (GND). Therefore, in the PMOS transistor P6, the gate voltage Vg≈the source voltage Vs≈the drain voltage Vd≈GND. Accordingly, the off resistance of the PMOS transistor P6 is smaller than the off resistance of the PMOS transistor P4.

Here, assuming that the device resistance of the PMOS transistor P4, the device resistance of the PMOS transistor P5, the device resistance of the PMOS transistor P6, and the device resistance of the NMOS transistor N3 are R _P4 , R _P5 , R _P6 , and R _N3 , respectively. The relationship of resistance is R _P4 > R _N3 + R _P5 + R _P6 . In this embodiment, the on-resistance and off-resistance of the transistor elements are collectively referred to as “element resistance”.

  The potential of the node vs is lowered to the ground level (GND) because the NMOS transistor N3 and the PMOS transistor P5 are on. When the node vs is lowered to the threshold value of the PMOS transistor P3, the PMOS transistor P3 is turned on, and the starting current flows to the bias circuit 12.

  When the bias circuit 12 starts to be activated by the activation current supplied by the supply element 22 in this way, the potential of the node vp and the potential of the node vn approach the potential of the operation stable point. The potential of the operation stable point of the node vp depends on the threshold voltage Vtp of the PMOS transistor P1, and vp = Vdd−Vtp. The potential of the operation stable point of the node vn depends on the threshold voltage Vtn of the NMOS transistor N21, and vn = GND−Vtn.

  Since the potential of the node vp is lowered, the PMOS transistor P4 changes from the off state to the on state, and changes from a very large off resistance to an on resistance.

  Accordingly, the on-resistance of the NMOS transistor N3 and the on-resistance of the PMOS transistor P5 gradually increase, and the potential of the node vs is gradually raised to the power supply level (Vdd).

  Also in the NMOS transistor N3, the gate voltage Vg is increased by increasing the on-resistance of the PMOS transistor P5, and the potential of the node vs2 is also raised to the power supply level (Vdd) by the PMOS transistor P4. Thereby, the off resistance of the PMOS transistor P6 becomes a very large off resistance.

Here, the relationship between the element resistances is R _P4 <R _N3 + R _P5 + R _P6 . As a result, when the potential of the node vp and the node vn becomes the potential of the above-described stable operation point (vp = Vdd−Vtp, vn = GND−Vtn), the potential of the node vs becomes the power supply level (Vdd), and the PMOS transistor P3 Turns off. Since the PMOS transistor P3 is turned off, the starting current does not flow through the bias circuit 12. Therefore, after the bias circuit 12 is activated, when the node vp and the node vn are at the potential of the operation stable point, it is possible to suppress the occurrence of a leakage current in which the activation current flows in the bias circuit 12.

  Therefore, in the bias circuit 12 of the present embodiment, the bias circuit 12 can be reliably started up, an unnecessary current can be prevented from flowing after the start-up is completed, and the bias circuit 12 can be operated normally.

  Note that when only one of the node vp and the node vn becomes the potential of the above-described operation stable point and the other does not become the potential of the operation stable point, only one of the on-resistances of the NMOS transistor N3 and the PMOS transistor P5 is present. Does not grow. From this, the potential of the node vs2 is maintained at the high impedance (Hiz) of the intermediate potential, and the potential of the node vs is not raised to the power supply level (Vdd), so that the starting current continues to flow. After that, when both the node vp and the node vn become the potential of the operation stable point, as described above, the starting current does not flow and the bias circuit 12 operates normally.

  As described above, when the activation circuit 14 of the semiconductor device 10 according to the present embodiment detects the failure of the operation of the bias circuit 12 by the detection circuit 20, the off-resistance of the PMOS transistor P4, the on-resistance of the NMOS transistor N3, and the PMOS transistor P5 The potential of the gate of the PMOS transistor P3 of the supply element 22 is controlled according to the sum of the ON resistance of the PMOS transistor P6 and the OFF resistance of the PMOS transistor P6. As a result, when the bias circuit 12 does not operate, the starter circuit 14 can control the on / off of the PMOS transistor P3 to supply the starter current to the bias circuit 12, thereby starting the bias circuit 12 reliably. Can be made.

  In addition, when the bias circuit 12 completes startup and reaches an operation stable point of vp = Vdd−Vtp and vn = GND−Vtn, the PMOS transistor P4 raises the potential of the node vs and stops supplying the startup current. Let Thereby, the starting circuit 14 can suppress an excessive starting current from flowing after the bias circuit 12 is started.

  Furthermore, since the startup circuit 14 detects the operation stable points vp = Vdd−Vtp and vn = GND−Vtn by the detection circuit 20, until the bias circuit 12 is completely started and becomes stable. The starting current does not stop. Therefore, it is possible to suppress the operation failure of the bias circuit 12.

  Note that the gate of the PMOS transistor P6 may be connected to the node vs instead of the node vs2 depending on the characteristics required for the circuit and the manufacturing process.

  Further, the connection destination of the activation detection terminal for detecting the power supply state (potential) of the bias circuit 12 in the bias circuit 12 is not limited to the present embodiment, and may be a place where the power supply state (potential) of the bias circuit 12 can be detected. That's fine.

In the above description, the drain of the PMOS transistor P3, which is the supply element 22 of the bias circuit 12, is connected to the node vn of the bias circuit 12. It may be connected.
(Second embodiment)
A case where the detection circuit 20 described in the first embodiment is applied to a bias circuit different from the first embodiment will be described. In this embodiment, as a specific example, a case where the present invention is applied to the bias circuit 12A shown in FIG. 7 will be described. FIG. 2 shows a circuit diagram of an example of a semiconductor device 10A that automatically activates the bias circuit 12A shown in FIG.

  As shown in FIG. 2, the bias circuit 12A includes a PMOS transistor P1, a PMOS transistor P2, an NMOS transistor N1, an NMOS transistor N2, and a resistor R1, as in the case shown in FIG.

  The PMOS transistor P1 and the PMOS transistor P2 are connected in the same manner as the bias circuit 12 shown in FIG. On the other hand, the gate of the NMOS transistor N1 is connected between the node vn and the drain of the NMOS transistor N2. The gate of the NMOS transistor N2 is connected by a node vr between the source of the NMOS transistor N1 and the resistor R1.

  The bias circuit 12A is configured such that the reference current Iref1 and the reference current Iref2 are equalized by equalizing the gate-source voltage of the NMOS transistor N2 and the voltage generated in the resistor R1 (reference current Iref1 × R1). Is generated.

  Similar to the bias circuit 12, the bias circuit 12A also has an operation stable point in a state where Iref1 = Iref2 = 0 (a state where a reference current does not flow). Specifically, if the gate-source voltage of the NMOS transistor N2 and the voltage generated in the resistor R1 (reference current Iref1 × R1) become stable when the voltage is 0 V, the reference current is a circuit current (bias current). Iref1 and the reference current Iref2 are not generated, and the operation becomes stable at Iref1 = Iref2 = 0.

  In the semiconductor device 10A shown in FIG. 2, the bias circuit 12A is reliably started in the same manner as described above by providing the start circuit 14 similar to that described above for the bias circuit 12A. It is possible to suppress an unnecessary current from flowing after the start-up is completed and to operate the bias circuit 12A normally.

As described above, the configuration of the bias circuit in the present invention is not limited to this embodiment, but has two or more appropriate detection nodes and an appropriate node through which the starting current can flow from the starting circuit 14. If it is.
(Third embodiment)
In the present embodiment, a case will be described in which the semiconductor device 10 described in the first embodiment includes a delay circuit that delays the time until the PMOS transistor P4 reaches the potential of the operation stable point.

  FIG. 3 shows a circuit diagram of an example of a semiconductor device provided with a startup circuit having a delay circuit.

  The semiconductor device 10B according to the present embodiment includes a startup circuit 14B. The activation circuit 14B of this embodiment includes a detection circuit 20, a supply element 22, and a delay circuit 24. The delay circuit 24 includes a folded current mirror circuit (current mirror circuit) including a PMOS transistor P7 and an NMOS transistor N4, and a capacitive element C1.

  The source of the PMOS transistor P7 is connected to the power supply voltage Vdd, and the source of the NMOS transistor N4 is connected to the ground GND. The gate of the PMOS transistor P7 is connected to the gate of the PMOS transistor P4 of the detection circuit 20, and the gate of the NMOS transistor N4 is connected to the node vn of the bias circuit 12. The drain of the PMOS transistor MP7 and the drain of the NMOS transistor N4 are connected.

  One end of the capacitive element C1 is connected to the power supply voltage Vdd, and the other end is connected between the PMOS transistor P7 and the NMOS transistor N4, and further connected between the PMOS transistor P4 and the PMOS transistor P7. ing.

  In the present embodiment, the potential of the gate of the PMOS transistor P4 varies according to the delay circuit 24. Therefore, the delay circuit 24 can suppress an increase in the gate potential of the PMOS transistor P4. As a result, the time until the potential of the gate of the PMOS transistor P4 reaches the potential of the operation stable point can be delayed.

  Therefore, in this embodiment, as in the above-described embodiments, the bias circuit 12 can be reliably started, and the time during which the start-up current flows transiently in the bias circuit 12 can be lengthened.

  Also in this embodiment, when the potential of the node vn becomes the potential of the operation stable point, the NMOS transistor N4 is turned on, the PMOS transistor P7 is turned on, and the PMOS transistor P4 is kept on. Similar to the example, it is possible to suppress an unnecessary current from flowing after the start-up is completed.

Note that the capacitance of the capacitor C1 may be determined according to circuit characteristics and a desired delay time.
(Fourth embodiment)
In this embodiment, another example of the delay circuit will be described.

  FIG. 4 shows a circuit diagram of an example of a semiconductor device provided with a startup circuit having a delay circuit different from the delay circuit 24 shown in the third embodiment.

  The semiconductor device 10BC of this embodiment and a starter circuit 14C are provided. The activation circuit 14C of this embodiment includes a detection circuit 20, a supply element 22, and a delay circuit 24C.

  The delay circuit 24C includes a folded current mirror circuit (current mirror circuit) including a plurality of stages of PMOS transistors and NMOS transistors. FIG. 4 shows a delay circuit 24 </ b> C having X−7 + 1 = Y4 + 1 stage folding mirror circuits.

  In the folding mirror circuit of each stage, the source of the PMOS transistor P (P7, P8, P9... PX) is connected to the power supply voltage Vdd, and the source of the NMOS transistor N (N4, N5, N6... NY) is the ground GND. It is connected to the. The drains of the PMOS transistors P (P7, P8, P9... PX) and the drains of the NMOS transistors N (N4, N5, N6... NY) are connected.

  The gate of the first-stage PMOS transistor P7 is connected to the node vp of the bias circuit 12. With n being an even number, the gate of the n-th stage PMOS transistor P and the gate of the n + 1-th stage PMOS transistor P are connected. The gate of the (n−1) th stage NMOS transistor N and the gate of the nth stage NMOS transistor N are connected.

  The gate of the PMOS transistor P4 of the detection circuit 20 is connected between the PMOS transistor PX at the final stage and the NMOS transistor NY.

  As a result, the ON and OFF of the NMOS transistor NY at the final stage is delayed in accordance with the number of stages of the folding mirror circuit, so that an increase in the potential of the gate of the PMOS transistor P4 can be suppressed. As a result, the time until the potential of the gate of the PMOS transistor P4 reaches the potential of the operation stable point can be delayed.

  Therefore, in this embodiment, as in the above-described embodiments, the bias circuit 12 can be reliably started, and the time during which the start-up current flows transiently in the bias circuit 12 can be lengthened.

  Note that each stage of the delay circuit 24C may be distributed in the semiconductor device 10C.

  The number of stages of the delay circuit 24C may be determined according to circuit characteristics and a desired delay time. Furthermore, the number of stages of the delay circuit 24C may be switched in accordance with circuit characteristics and a desired delay time.

In the third and fourth embodiments, the delay circuit is provided in the starting circuit. However, the folding mirror circuit provided in the semiconductor device may be shared. In order to supply an appropriate current from the bias circuit to the circuit of each block in the semiconductor device, a plurality of folding mirror circuits with different mirror ratios (ratio of adjusting the output current to the input current) are connected. A semiconductor device may be generally used. In such a case, these folding mirror circuits may be shared as a delay circuit.
(Comparative Example 1)
As a comparative example, a method of inputting an activation signal from the outside to the bias circuit 12 and the bias circuit 12A will be described.

  In the case of a system in which an activation signal is input from the outside, since the node voltages of the bias circuit 12 and the bias circuit 12A are not detected, there may be insufficient operation failure that may occur depending on the use environment and various conditions. Since the activation signal is not input again, it is not restarted. Accordingly, there are cases where the bias circuit 12 and the bias circuit 12A cannot be reliably started and cannot be stably operated.

In order to activate the bias circuit 12 and the bias circuit 12A, the activation signal must be continuously input until the bias circuit 12 and the bias circuit 12A are reliably activated and reach the potential of the operation stable point.
(Comparative Example 2)
As a comparative example, a case where a conventional automatic startup system startup circuit is applied to the bias circuit 12 and the bias circuit 12A will be described. FIG. 8 shows a circuit diagram of an example in the case where a conventional startup circuit is applied to the bias circuit 12 shown in FIG. FIG. 9 is a circuit diagram showing an example in which a conventional starter circuit is applied to the bias circuit 12A shown in FIG.

  The activation circuit 114 of the semiconductor device 100 illustrated in FIG. 8 includes a detection circuit 120 and a supply element 122. The supply element 122 includes a PMOS transistor P3. The detection circuit 120 includes a PMOS transistor P4 and an NMOS transistor N3.

  The activation circuit 114A of the semiconductor device 100A illustrated in FIG. 9 includes a detection circuit 120A and a supply element 122A. The supply element 122A includes an NMOS transistor N3. The detection circuit 120A includes a PMOS transistor P3 and an NMOS transistor N4.

  The starter circuit 114 and the starter circuit 114A have a function of preventing a state in which the reference current Iref1 = reference current Iref = 0 is generated by forcibly supplying the starter current to the bias circuit 12 and the bias circuit 12A, respectively, and generating a reference current. ing.

  The starter circuit 114 and the starter circuit 114A have a problem in the circuit configuration itself, and current continues to flow through the starter circuit 114 and the starter circuit 114A, respectively. Depending on element variations, etc., a large current flows and current consumption increases. May end up.

  In some cases, the starting current continues to flow through the bias circuit 12 and the bias circuit 12A, respectively. In such a case, as described above, depending on element variations and the like, a large starting current continues to flow, and the bias circuit 12 and the bias circuit 12A operate abnormally.

  On the other hand, matching of circuit element sizes has been attempted, but it is difficult to completely eliminate element variations and the like.

  Furthermore, with the recent trend of lower current consumption, the bias current has become a very small current level on the order of several uA to several nA. Therefore, the operation failure of the bias circuit 12 and the bias circuit 12A is more likely to occur.

  As described above, according to each semiconductor device of each of the above-described examples in the present embodiment (hereinafter, the reference numerals of the respective parts are omitted when the examples are collectively referred to), the operation of the bias circuit is prevented from occurring in the detection circuit. When detected, the PMOS transistor P3 of the supply element 22 depends on the off resistance of the PMOS transistor P4, the on resistance of the NMOS transistor N3, the on resistance of the PMOS transistor P5, and the off resistance of the PMOS transistor P6. To control the gate potential.

  As a result, when the bias circuit does not operate, the starter circuit can turn on the PMOS transistor P3 to supply the starter current to the bias circuit, thereby starting the bias circuit with certainty.

  When the bias circuit completes starting and reaches the stable operating point of vp = Vdd-Vtp and vn = GND-Vtn, the PMOS transistor P4 raises the potential of the node vs to stop the supply of the starting current. . Thereby, the starting circuit can suppress an excessive starting current from flowing after the bias circuit is started.

  Furthermore, since the startup circuit detects vp = Vdd−Vtp and vn = GND−Vtn, which are operation stable points, by the detection circuit, until the bias circuit is completely started and becomes stable, the startup current Does not stop. For this reason, it is possible to suppress the occurrence of malfunction of the bias circuit.

  Furthermore, in each of the above embodiments, the detection circuit is provided with a plurality of elements (NMOS transistor N3, PMOS transistor P5, and PMOS transistor P6) between the node vs and the ground GND. Thereby, the difference between the element resistance of the PMOS transistor P4 provided between the node vs and the power supply voltage Vdd and the sum of the element resistances of the plurality of elements between the node vs and the ground GND can be increased. Therefore, the bias circuit can be started stably.

  Therefore, in each semiconductor device of each of the above embodiments, it is possible to reliably start the bias circuit in the automatic starting method without using a special process or the like, and to suppress unnecessary current from flowing after the starting is completed. .

  In each of the above embodiments, the resistor R1 of the bias circuit is connected to the ground GND, but may be configured to be connected to the power supply voltage Vdd. A circuit diagram of an example of such a semiconductor device 10 is shown in FIG. Even in such a semiconductor device 10D, the bias circuit 12 can be activated as in the above embodiments.

  In addition, the configurations and operations of the semiconductor devices, bias circuits, start-up circuits, supply elements, and detection circuits described in the other embodiments are examples, and the situation is within the scope of the present invention. It goes without saying that it can be changed according to the situation.

10, 10A, 10B, 10C, 10D Semiconductor device 12, 12A Bias circuit (constant current generation circuit)
14, 14B, 14C, 14D Start-up circuit 20, 20D detection circuit (control unit)
22, 22D supply element 24, 24C delay circuit

Claims (8)

A supply element that includes a control terminal and supplies a starting current to the constant current generation circuit in accordance with a voltage applied to the control terminal;
A first element connected between a control node connected to a control terminal of the supply element and a first potential portion; and a connection between the control node and a second potential portion different from the first potential portion. A plurality of second elements, and a controller that controls the supply of the starting current by the supply element;
With
When the constant current generating circuit is in the first power supply state, the control unit has an element resistance of the first element larger than a sum of element resistances of the plurality of second elements, and the constant current When the generation circuit is in the second power supply state, the element resistance of the first element is smaller than the sum of the element resistances of the plurality of second elements.
Start-up circuit. In the control unit, the first element and the plurality of second elements are connected to a predetermined detection node of the constant current generation circuit, and according to a potential of the detection node, the first power supply state and Detecting which of the second power states is
The start-up circuit according to claim 1. The supply element and the first element are first conductivity type transistors,
The plurality of second elements are, in order from the closest to the control node, a second conductivity type transistor connected in series and at least one of the first conductivity type transistors.
The start-up circuit according to claim 1 or 2. A delay circuit that delays a time from when the first element reaches a potential according to the second power supply state from a potential according to the first power supply state;
The starting circuit according to any one of claims 1 to 3. The delay circuit includes a current mirror circuit and a capacitive element connected to a control terminal of the first element.
The start-up circuit according to claim 4. The delay circuit includes a plurality of stages of current mirror circuits according to a delay time.
The start-up circuit according to claim 4. A constant current generating circuit;
The start-up circuit according to any one of claims 1 to 6, and
A semiconductor device comprising: A supply element that supplies a starting current to the constant current generation circuit according to a voltage applied to the control terminal, and a first node connected between the control node connected to the control terminal of the supply element and the first potential portion. A control unit that includes an element and a plurality of second elements connected between the control node and a second potential part different from the first potential part, and that controls the supply of the starting current by the supply element; A method for starting a semiconductor device comprising:
When the constant current generation circuit is in the first power supply state, the element resistance of the first element is made larger than the sum of the element resistances of the plurality of second elements, and the constant current generation circuit is generated by the supply element. Supplying the starting current to
When the constant current generation circuit is in the second power supply state, the element resistance of the first element is made smaller than the sum of the element resistances of the plurality of second elements, and the supply of the starting current by the supply element Stopping the process,
For starting a semiconductor device comprising: